During problem analysis it was found that traffic in vlan 950 on the switch “ekb_s9312_dmz2” was coming from interface eth-trunk2, but there was no outgoing traffic in the vlan 950 on the interface eth-trunk5 such as follows.
<ekb_s9312_dmz2>disp vlan 950 statistics

In case of mirroring incoming and outgoing traffic (from sgsn and ggsn) such mac-address table on the switch ekb_s9312_dmz2 is normal, but at the same time no any mirrored ethernet frames were switched and sent out through outgoing interface eth-trunk5, because switch will drop ethernet frames which come through the interface which has learned these frame’s destination mac address. For example, A is a source mac-address, B is a destination mac-address, and switch has learned A's mac-address, when B sends packets to A, and the intermediate switch gets these packets from mirroring traffic, the switch will drop these packets.
In this situation (if there is only one incoming interface and one outgoing interface in the vlan) we can disable mac address learning function in the vlan 950 and rspan will work.

Suggestions

This issue can happen only if there are following preconditions:

bi-directional traffic are mirrored;

there is (are) transport network switch (switches).

The way to avoid this issue is to disable mac learning function in the rspan vlans on the all intermediate switches.
If disabling mac learning function is unsafe, use two different rspan vlans for incoming and outgoing mirrored traffic respectively.